Francis i



(Mode1.)

F. I. HOEFL-E.

' AUGER.

No. 430,344. g Patented June 17,1890.

IIVVEIVTOR:

JJW By ATTORNEYS.

UNITED STATES PATENT OFFICE.

FRANCIS I. HOEFLE, OF \VILMINGTON, OHIO, ASSIGNOR TO CHARLES H. IRWIN, OF SAME PLACE.

AUGER.

SPECIFICATION forming part of Letters Patent No. 430,344, dated June 17, 1890.

Application filed July 26, 1889. Serial No. $18,783. (Modeh) To all whom it may concern.-

Be it known that I, FRANCIS I. HOEFLE, of \Vilmington, in the county of Clinton and State of Ohio, have invented a new and useful Improvement in Angers, of which the following is a full, clear, and exact description.

My invention relates to an improvement in angers, and has for its object to so construct the tool that it will pass through the article to be bored with the least possible friction, and also to so form the anger that a center will not be needed.

The invention consists in the novel construction of the anger, as will be hereinafter fully set forth, and pointed out in the claims.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar figures of reference indicate corresponding parts in all the views.

Figure 1 is a partial side elevation of an anger constructed in accordance with my invention. Fig. 2 is a transverse section on line as m of Fig. 1; and Fig. 3 is a partial side elevation of an anger provided with double cutters, the auger illustrated in Fig. 1 being provided with a single cutter only.

1n carrying out the invention the screw of the anger is integral with the shank, and is formed by casting, forging, drawing, or otherwise manipulating the metal.

10 is the shank, and 1]. is the body of the bit, having a spiral twist, and a cross-section at all points substantially the form of a wedge, as shown in Fig. 2, the inner or upper side 12 of which is concave and the outeror lower side 13 convex. The point of the wedge is outermost and forms the continuous spiral knifeedge 14. The spiral conoavo-convex wedgeshape body is wound or formed upon and exterior to an imaginary straight line y y, Fig. 1, which is, the longitudinal central axisof the shank 10 and gimlet-point 15. Thus while the spiral is continuous and uniform in shape at every point throughout its length it presents to the eye the appearance of a series of cone-like oonvolntions, the inclined or spiral heads of each joining the point of the one above. The lower end of the spiral body terminates in the single cntter'16, (shown in Fig. 1,) ora double cutter (shown in Fig. 2) may be provided.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. As an improved article of manufacture, an anger, the spiral body of which is concavoconvex wedge shape in cross-section throughout its length and wound or formed upon and exteriorly to a straight line through the longitudinal axis of the shank, the point of the wedge being outermost and forming the continuous knife-edge, substantially as set forth. 2. As an improved article of manufacture, a gimlet-pointed auger formed with a spiral body of concavo-convex wedge shape in crosssection throughout its length, the point of the wedge being outermost and forming the continuous knife-edge, the said body being wound or formed upon and exteriorly to a straight line through the longitudinal axis of the shank and bit, and a cutter at the lower terminal of the spiral body, substantially as set forth.

FRANCIS I. HOEFLE.

WVitnesses:

F. M. WVEGMAN, G. P. THORPE. 

